The present invention relates to Fluid Catalytic Cracking (FCC) catalysts and the process for preparation wherein the value added FCC catalyst composition offering dual functions of simultaneous passivation of metals and also for enhancement of catalytic activity of host Resid Fluid Catalytic Cracking (RFCC) catalyst for processing heavy metal laden feeds in petroleum processing industry. This invention also relates to various value addition processes of spent FCC catalyst.
Fluid Catalytic Cracking (FCC) catalysts used today in cracking process are not so cost effective hence increasing cost of crude is forcing refineries to process the hydrocarbon feeds having high carbon residue, nitrogen, aromatics and heavy metal contaminants such as nickel and vanadium to be efficiently used in the refinery industry. Among all the contaminants present in feeds, metal contaminants pose the greatest challenge, as some of them permanently cripple the catalytic activity while some metals produce undesired products such as coke and dry gas. Nickel is well known for dehydrogenation of feed and products under normal FCC operation conditions thereby producing higher coke and dry gas. These effects are predominant with catalysts having higher surface area. Vanadium, unlike nickel, is known for zeolite destroying property and for even worse effects by hopping from aged catalyst particle to fresh catalyst particle while carrying out the destructive action. Vanadium pentoxide, formed during severe regeneration operation, gets converted to vanadic acid which reacts with structural alumina of zeolite and also with structure supporting rare earth species. Presence of vanadium in the feed can permanently reduce activity of the FCC catalyst. Processing such feeds create increasing demand for catalysts having higher metal tolerance. Such a process which processes heavy feeds sourced from streams such as inter oil, heavy oil, deashphalted oil, short residue, heavy gas oil, coker gasoil having nickel in the range 8-50 ppm and vanadium in the range 15-120 ppm while employing high matrix metal tolerant catalysts is known as Resid Fluid Catalytic Cracking (RFCC). Spent catalysts in these processes, accumulate total metals in the range 1-3 wt %. As discussed earlier, nickel and vanadium are the most prominent among all the metals requiring remedy for their undesired properties. Besides, as the catalyst produces higher coke while processing resid feeds, for withstanding higher temperature of catalyst regeneration process, hardware needs to have improved metallurgy. Catalysts employed for RFCC operations need to be robust towards high temperature regeneration, steam stripping and metal environment under the dynamic conditions of RFCC operation. Due to higher rate of catalyst deactivation in presence of metals and operational severity, catalyst make-up rate is higher in case of RFCC, which is in the range 4-15 wt % of inventory against 0.4-5 wt % in case of FCC. It may be noted, due to lower deactivation rate and having lower metals in spent FCC catalysts, there is a significant activity left in such spent catalysts and used for initial start-up or for make-up in RFCC/FCC units.
Catalyst manufacturers, often produce less robust catalysts which are cheaper and produced from normal NH4Y zeolite and conventional binders. Such catalysts on withdrawal from the plant cannot be re-employed for start-up or for make-up in case of RFCC units. On the contrary, RFCC catalysts are produced from thermally stable high silica-alumina USY zeolites and employing components desired for high temperature operation, enhancing metal stability etc. Inference can be drawn; catalysts employed for VGO/soft feed processing may not be suitable for RFCC operation. RFCC operation, besides employing high active thermally stable catalysts may additionally use metal passivator additives. Though, it is desirable to reuse spent or E-catalyst from FCC for RFCC start-up or for make-up in view of improving the economy of process, often due to requirement of higher metal and thermal stability, spent catalysts could not be exploited for RFCC. The present invention describes a process and composition for the preparation of RFCC catalyst from spent FCC catalyst for further use in RFCC.
U.S. Pat. No. 5,520,797 and U.S. Pat. No. 4,359,379 describe processes for the fluid catalytic cracking of heavy oils rich in Ni and V by withdrawing a portion of ferrite-containing catalyst particles circulating in a fluid catalytic cracking apparatus, by using a magnetic separator.
U.S. Pat. No. 5,188,995 refers to a process in which spent metal-contaminated zeolite-containing catalytic cracking catalyst is reactivated by a process which comprises contacting the spent catalyst with at least one dissolved carboxylic acid and at least one antimony compound. This invention more particularly describes a method of reactivating spent, metal-contaminated zeolite-containing catalytic cracking catalysts. In another aspect, this invention relates to a catalytic cracking process employing a reactivated spent catalytic cracking catalyst.
U.S. Pat. No. 5,151,391 refers to a process in which, spent metal contaminated zeolite-containing catalytic cracking catalyst composition is reactivated by a process which comprises contacting with an aqueous solution of HCl and/or HNO3 and/or H2SO4. Thus reactivated catalyst composition can be employed in a catalytic cracking. Further this invention relates to a method of reactivating spent, metal-contaminated zeolite-containing catalytic cracking catalysts. In another aspect, this invention relates to a catalytic cracking process employing a reactivated spent catalytic cracking catalyst.
U.S. Pat. No. 5,888,919 refers to a process in which a spent zeolite-containing hydrocarbon cracking catalyst is treated by regenerating it to remove carbonaceous deposits. A portion of the regenerated catalyst is withdrawn from the circulating catalyst inventory of a hydrocarbon processing unit and slurried with a liquid containing an activating agent. This invention relates to process for improving the activity of fluid catalytic cracking (FCC) or moving bed cracking (TCC) catalyst, including any additives containing zeolitic material as one of the active components and which may be employed with each type catalyst, which process can be integrated with the operations of the hydrocarbon processing unit in which the catalyst is employed.
U.S. Pat. No. 4,919,787 refers to a process for an improved method for passivating metals in a hydrocarbon feedstock during catalytic cracking. Further this invention involves contacting the feedstock with a passivating agent comprising a precipitated porous rare earth oxide, alumina, and aluminum phosphate precipitate. The passivating agent may be coated on a cracking catalyst, be part of the matrix of a cracking catalyst, or be added to the cracking operation as discrete particles.
Patent number EP73874B1 discloses Immobilisation of vanadia deposited on catalytic materials during the conversion of oil that contains coke precursors and heavy metals. US application 20100025297A1 discloses additives for metal contaminant removal. catalytic cracking additives comprising a metal trapping material; and a high activity catalyst. This invention is directed to processes for the catalytic cracking of feedstock comprising contacting said feedstock under catalytic cracking conditions with a composition comprising a bulk catalyst and a catalytic cracking additive, wherein the catalytic cracking additive comprises a metal trapping material; and a high activity catalyst.
Therefore, there is a need to provide an improved process and a catalyst composition for converting low activity, low metal tolerant spent FCC catalyst to an efficient catalyst composition to be used in RFCC process for enhancing metal tolerance and also for enhancing catalytic activity of host catalyst for a more efficient and cost effective method.
The present invention is aimed at avoiding or overcoming the difficulties or limitations encountered to provide an improved process and a catalyst composition for catalytic cracking of heavy oils in petroleum processing industry.
It will be advantageous to have a composition and an efficient process to prepare the composition for employing low activity, low metal tolerant spent FCC catalyst for further use in RFCC in enhancing metal tolerance and also in enhancing catalytic activity of host catalyst.
It will be advantageous to have a product from spent catalyst, which will enhance the catalytic activity and selectivity of spent catalysts in adverse RFCC operation conditions.
It will also be advantageous to have an efficient process and a product from spent catalyst, which will enhance the catalytic activity and selectivity of spent catalysts in adverse RFCC operation conditions.
Furthermore, a product and process for improving thermal and metal stability of spent catalyst through impregnation with metal passivation composition, while this value added spent catalyst can be employed as an additive in RFCC process will be beneficial.
Still further, a process for the preparation of a thermal and metal stable RFCC catalyst from spent catalyst for processing metal laden heavy feeds will be advantageous.
It will be also advantageous to have a process, by which application of metal passivation composition on spent catalyst, enhances crystallinity and surface area of a host catalyst.
Process and composition for preparation of a thermal and metal tolerant catalyst from spent FCC catalyst which can be employed in RFCC process as an additive or as a whole metal tolerant RFCC catalyst will be beneficial.
The present invention is aimed to provide an efficient process and a composition for employing low activity, low metal tolerant spent FCC catalyst for further use in RFCC in enhancing metal tolerance and also in enhancing catalytic activity of host catalyst.
It is another advantage of the invention to provide an efficient process and a product from spent catalyst, which will enhance the catalytic activity and selectivity of spent catalysts in adverse RFCC operation conditions.
It is yet another advantage of the invention to provide a process for improving thermal and metal stability of spent catalyst through impregnation with metal passivation composition, while this value added spent catalyst can be employed as an additive in RFCC process.
It is still another advantage of the invention to develop a process for the preparation of a thermal and metal stable RFCC catalyst from spent catalyst for processing metal laden heavy feeds.
It is yet another advantage of the invention to provide a process, by which application of metal passivation composition on spent catalyst, enhances crystallinity and surface area of a host catalyst.
It is yet further advantage of the invention to develop a process and composition for preparation of a thermal and metal tolerant catalyst from spent FCC catalyst which can be employed in RFCC process as an additive or as a whole metal tolerant RFCC catalyst.